Steerable Positioning Element

ABSTRACT

A display system comprising a steerable display having a monocular field of view of at least 1 degree, positioned within a scannable field of view of at least 20 degrees, the steerable display positioned for a user. In one embodiment, the steerable display is positioned for the user&#39;s fovea.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 62/777,061, filed on Dec. 7, 2018, and U.S. ProvisionalPatent Application 62/902,377, filed on Sep. 17, 2019, and incorporatesboth applications by reference in their entirety.

FIELD OF THE INVENTION

The present application relates to near-eye display systems, and inparticular to a steerable positioning element in a near-eye display.

BACKGROUND

Near-eye displays have the competing requirements of displaying imagesat a high resolution, over a large field of view (FOV). For manyapplications in virtual and augmented reality, the field of view shouldbe greater than 90 degrees, and ideally the binocular field of viewwould extend past 180 degrees. At the same time, the resolution of thedisplay should match that of the human visual system so that little orno pixelation is perceived in the virtual images. Combining these tworequirements in a single system presents a number of challenges. Toavoid the appearance of pixelation, the resolution needs to be on theorder of 0.01-0.02 degrees per pixel. Over a 90-degree square field ofview, this corresponds to 4.5 k×4.5 k pixels per eye or higher.Achieving such resolutions is challenging at the level of the panel, thedrive electronics, and the rendering pipeline.

Additionally, optical systems that can project wide FOV images to theuser with sufficiently high resolution over the entire field of view arealso difficult to design. Systems architectures that are able to presentthe user with high resolution images over a wide field of view, whilesimultaneously reducing the rendering, data rate, and panel requirementswill enable new applications for augmented and virtual reality systems.

LIST OF FIGURES

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1A is an illustration of a first embodiment of a steerablepositioning element.

FIGS. 1B and 1C are a perspective view and a cross-section of anotherembodiment of a steerable positioning element.

FIG. 1D is an illustration of another embodiment of the steerablepositioning element.

FIG. 1E is an illustration of another element of the steerablepositioning element.

FIG. 1F is a cross-section of the embodiment of FIG. 1E.

FIG. 2 is a block diagram of one embodiment of the system.

FIG. 3 is a block diagram of one embodiment of the steerable positioningelement.

FIG. 4A is a flowchart of one embodiment of using a steerablepositioning element.

FIG. 4B is a flowchart of one embodiment of positioning verification forthe steerable positioning element.

FIG. 4C is an illustration of one embodiment of the movement of thedisplay, in a steerable display.

FIG. 5 is a flowchart of another embodiment of using a steerablepositioning element.

FIG. 6 is a flowchart of one embodiment of controlling the use of thesteerable element.

DETAILED DESCRIPTION

The present application discloses a steerable positioning element whichmay be used to enable a steerable display. In one embodiment, thesteerable positioning element may be a mirror, lens, prism, dichroicmirror, switchable crystal or other positioning element. The steerabledisplay in one embodiment is designed to be positionable to provide ahigh resolution display in the area where the user's fovea is located.The “fovea” is the small depression in the retina of the eye wherevisual acuity is highest. In another embodiment, the steerable displaymay be positioned to provide a heads-up display, or a sprite, in aparticular location. The location may be based on the user'ssurroundings, the user's gaze, other external data, or another factor.The steerable display may be used in a virtual reality and/or anaugmented reality display, in one embodiment. The steerable display mayalso be used for any other purpose, in which a high resolution displayis designed to be positioned.

The following detailed description of embodiments of the invention makesreference to the accompanying drawings in which like references indicatesimilar elements, showing by way of illustration specific embodiments ofpracticing the invention. Description of these embodiments is insufficient detail to enable those skilled in the art to practice theinvention. One skilled in the art understands that other embodiments maybe utilized and that logical, mechanical, electrical, functional andother changes may be made without departing from the scope of thepresent invention. The following detailed description is, therefore, notto be taken in a limiting sense, and the scope of the present inventionis defined only by the appended claims.

FIG. 1A illustrates one embodiment of a steerable positioning element.In one embodiment, the system 110 includes display element 120 supportedby gimbals 155 and support structure columns 125.

The display element 120 may pivot along two axes. In one embodiment, thesystem includes two gimbals 155, each of which provides pivoting alongone axis. The pivoting of the display element 120 is controlled by thepiezoelectric elements 135 mounted to flexible arms 130, acting as theX-axis controller and the Y-axis controller. In one embodiment theflexible arms 130 are made of metal. In one embodiment, the flexiblearms support the piezoelectric elements 135. The flexible arms 130provide a static force against the side of the assembly, to ensure thatpiezoelectric elements 135 apply a force normal to the driving surfaceof the display element 120 as the piezoelectric element 135 is actuatingand remains in contact with the display element 120 when at rest.

In one embodiment, the range of motion of the display element 120 may be+/−10 degrees along both the X and Y axis. The drivers 145 drive thepiezoelectric elements 135 to control motion.

In one embodiment, microcontroller 147 receives control data from thesystem, and controls the drivers 145 to drive the piezoelectric elements135, to move the display element 120.

In one embodiment, position sensor 140 is used to verify the actualposition of the display element 120. In one embodiment, position sensor140 may be one or more magnetic sensors which can sense the relativechange in a magnetic field of one or more magnets associated with thedisplay device. In one embodiment the magnets are positioned near theouter diameter of the display element 120. In one embodiment, twomagnets are positioned 90 degrees apart radially. In one embodiment, themagnets and associated magnetic sensors are positioned opposite thedrive surfaces. This provides minimal cross-coupling, and the mostaccurate measurement.

In one embodiment, the weight of the drive element is balanced by theweight of the magnet on the display element 120. The magnets may be rareearth magnets, in one embodiment. The magnetic sensors are placed inclose proximity to the magnets. In another embodiment, four magnets maybe used. In one embodiment, in a four magnet configuration two magnetsare positioned opposite the drive elements and two additional magnetsare placed further away from the display element. This adds more mass tothe system, but provides the ability to cancel other magnetic fields inthe space, including the earth's magnetic field, for more accuratemeasurement of the changes in the magnetic field based on the movementof the display element 120. In one embodiment, the magnetic sensors areHall effect sensors. In one embodiment, the magnetic sensors aremagnetometers.

In one embodiment, one or more additional magnetic sensors are used tomeasure the earth's magnetic field, or other ambient magnetic fields. Inone embodiment, the impact of the ambient magnetic fields aresubtracted, to negate its impacts on the display element positionmeasurements. In one embodiment, the additional sensors are oriented tobe approximately aligned with the measurement sensors on the assembly.In one embodiment, a single 3-axis magnetic sensor may be used. In oneembodiment, a differential sensor may be used.

In one embodiment, the calculation comparing the actual position to theinstructed position occurs on a processor, as will be described withrespect to FIG. 2. In another embodiment, the positioning element may becontrolled using an analog control circuit, that does not utilize amicrocontroller 147.

The display element 120 may be a mirror, lens, prism, holographicoptical element (HOE), liquid crystal polymer, and/or another elementutilized in directing light for a steerable display. In one embodiment,the display element 120 may be a Fresnel reflector, diffractive element,surface relief grating, light guide, wave guide, or volume hologram.

In one embodiment, piezo-electric elements 135 are actuators to move thedisplay element 120. Alternatively, the piezo-electric elements 135 maybe replaced magnetic and/or inductive elements, nanomotors,electrostatic elements, or other devices which enable the movement ofthe display element 120 with the precision and speed needed for adisplay system.

FIG. 1B is a top view of the steerable positioning element of FIG. 1A.

FIG. 1C is another embodiment of the steerable positioning element, inwhich a flexible printed circuit board 152 is added, and themicrocontroller is moved to a separate board. In one embodiment, theflexible printed circuit board 152 weaves in, as shown. This makes thesteerable positioning element a little lighter.

The tables below illustrate exemplary configurations of the optical andphysical characteristics of one embodiment of the steerable positioningelement. Note that while these tables show measurements, and in someinstances ranges of a preferred embodiment, variations from theseranges, and especially additional precision, may be preferred whenpossible. Additionally, while some ranges are provided, the system isnot limited to these ranges, in one embodiment.

In one embodiment, a system may include two mirrors.

In one embodiment, a fast moving element may be designed to match themovement of the eye in speed, with a small angle movement range of 0.3°in 300 μs and a large angle movement range of 2°-20° in 300 μs. Such afast-moving element may move every frame and can ignore saccades becausethe movement speed is fast enough, so it is not perceptible by a user.

A medium fast-moving display element in one embodiment also can moveevery frame, with a small angle movement range of 0.3° in 4 ms and alarge angle movement range of 2°-20° in 8 ms-50 ms. In one embodiment,this configuration permits saccades to settle by the time the eyesettling time begins.

A medium slow mirror in one embodiment has a small angle movement rangeof 0.6° in 9 ms and a large angle movement range of 2°-20° in 8 ms-50ms. In one embodiment, the medium slow mirror moves at approximately thesame speed as the medium fast mirror over larger angles, but more slowlyover smaller angles. However, even the medium slow mirror in oneembodiment can move every frame.

A slow mirror has a small angle movement range of 0.15° in 16 ms and alarge angle movement range of 2°-20° in 20 ms-100 ms. Because of itsslower speed, the slow mirror utilizes a blank frame during movement, inone embodiment. In one embodiment, the blank frame may be a subframe fordisplays capable of subframe blanking. In one embodiment, a slow mirrorutilizes saccadic masking, and relies on the eye settling time to ensurethat the user does not perceive the motion of the display controlled bythe mirror.

In one embodiment, the system is designed to move the mirror during thetime the display is off. For most OLED based VR displays, the duty cycleis in the range of 20% (that is, the display itself is only on for 20%of the frame time). The steerable display can be moved during the timewhen the display is off. The specific angles, speeds, and configurationdetails discussed are of course merely exemplary. A faster, slower, orintermediate mirror having different specifications may be used.

The below tables should be considered exemplary configurations. One ofskill in the art would understand that these aspects may be variedwithout departing from the scope of the invention.

FIG. 1D illustrates another embodiment of the steerable positioningelement 111. In one embodiment, the system 111 includes display element174 supported by flexible arms 170 and support structure base 160.

The display element 174 may pivot along two axes. The pivoting of thedisplay element 174 is controlled by the piezoelectric elements 172. Inone embodiment, the range of motion may be +/−18 degrees along both theX and Y axis. The drivers 164 drive the piezoelectric elements 172 tocontrol motion.

Microcontroller 176 receives the control data from the system andcontrols the drivers to move the display element 174. Position sensor168 is used to verify the actual position of the display element 174. Inone embodiment, the calculation comparing the actual position to theinstructed position occurs on a processor, as will be described below.

The display element 174 may be a mirror, lens, prism, holographicoptical element (HOE), liquid crystal polymer, adjustable mirror,tunable prism, acousto-optical modulator, adjustable display panel, acurved mirror, a diffractive element, a Fresnel reflector and/or anotherelement utilized in directing light for a steerable display. In oneembodiment, the display element 174 may be a Fresnel reflector,diffractive element, surface relief grating, light guide, wave guide, orvolume hologram.

In one embodiment, piezo-electric elements 172 are actuators to move thedisplay element 174. Alternatively, the piezo-electric elements 172 maybe replaced magnetic and/or inductive elements, nanomotors,electrostatic elements, or other devices which enable the movement ofthe display element 174 with the precision and speed needed for adisplay system.

FIGS. 1E and 1F are a perspective view and a cross-section of anotherembodiment of a steerable positioning element. The display element 180is supported in position by a plurality of positioning columns 184. Thepositioning columns 185 enable the movement of the display element 180.The positioning columns 185 are supported by base structure 182.Although not shown, this embodiment also includes a microcontroller andposition sensor.

The cross-section in FIG. 1F shows the elements of the positioningcolumns 185 and the central support 188, of the embodiment of FIG. 1E.In one embodiment, the system includes two or more positioning columns192, and central support 188. The central support 188 in one embodimentis positioned in the center of the display element 180 and provides astable point around which the display element tilts. Each positioningcolumn 192 in one embodiment includes an actuator 198, a moving supportstructure 196, and a tilt top 194.

In one embodiment, the actuator 198 is a piezoelectric element whichmoves the moving support structure 196 up and down. Alternatively, theactuator 198 may be a magnetic and/or inductive element, nanomotor,electrostatic element, or other actuator mechanism which enables themovement of the moving support structure 196 with the precision andspeed needed for a display system.

The moving support structure 196 moves up and down and has attached atilt-top 194. The tilt top 194 in one embodiment is round or has arounded top which fits into a notch 190 in the display element 180. Inone embodiment, the connection between the moving support structure 196and the tilt-top 194 is magnetic.

The tilt top 194 enables the display element 180 to be tilted by movingup and down. Because the tilt top 194 is smooth and fits into the notch190, the tilt top maintains contact with the display element 180.

In one embodiment, the tilt top 194 is a freely rotating sphere, coupledto the moving support structure 196 and the notch 190 via magneticforce. In this way, the system can utilize an actuator with fast up-downmotion capabilities to provide a range of motion to the display element180. The range of motion, and capabilities of the display element arediscussed below with respect to the Tables 5 through 6.

Tables 1 and 2 illustrate exemplary optical, physical, and othercharacteristics for a first configuration of the steerable mirror.

TABLE 1 One Embodiment Comment Optical and Physical CharacteristicsDeflection angle ±12° X axis; At least +/−12 degrees in both axes ±18° Yaxis (mechanical) Full Field of view (geometrical 55° System also has a10 mm clear aperture. This opening angle) refers to full field of viewopening when scanning from one extreme to the other. Instantaneous FOVis 10 deg Center of rotation On mirror May be up to 1.35 mm belowsurface center Accuracy vs Set-point ±1 arc minutes Up to ±2 arc minutes(absolute precision) Accuracy vs feedback ±0.25 arc Up to ±0.33 arcminutes (relative precision) minutes Repeatability RMS (typical) 0.1 arcminute Up to 0.3 arcmin (90 μrad) (30 μrad) Beam Stepping Time Smallstep angle (mech.) 0.5° No less than 0.35° Small Step Settling criteria97% of position 98% of position (within 1 arc min of final accuracy(within 1 arc destination) min of final destination) Small step settlingtime <2 ms Less than 4 ms Large Step Settling criteria 99.9% of At least99.8% of position (within 2 arc min) accuracy position (within 1 arcmin) Large step settling time <20 ms Less than 30 ms Mirror diameter 10mm diameter Reflectivity >95% Mirror flatness lambda/4 Operationwavelength Visible (450 nm-640 Short IR (700 nm-800 nm) nm) Typicalincident beam circular, 8 mm diameter Typical angle of incidence 45°with respect to the vertical reference line

TABLE 2 One Embodiment Comment Other Characteristics Footprint 8 mm × 8mm Up to 12 mm × 12 mm Height 2 mm Up to 5 mm Scanning or point & shoot?Point and Shoot Mechanical clamping Edge slots in Screws as back uppackaging Gravitational influence None Magnetic shielding Not-requiredOptical Mirror coating Protected Silver or enhanced aluminum Opticalpower LED illumination, mW May include laser range illumination Controlinterface SPI, I2S, I2C, PWM Power consumption <50 mW (DC) <10 mW (DC)Operating temperature −20° C. to 65° C. At least 0° C. to 40° C. Storagetemperature −40° C. to 85° C. Shock & vibration Shock according to DINrequirements EN 60068-2-27 Cycle life 220M full cycles At least 95M fullcycles Life time 7 years 3 years Compliance with RoHS

Tables 3 and 4 illustrate exemplary optical, physical, and othercharacteristics for a second configuration, associated with thesteerable positioning element of FIG. 1A.

TABLE 3 One Embodiment System Design Considerations Optical and PhysicalCharacteristics Deflection angle ±8.5° X axis; ±8.5° Mirror deflectionangle is designed in conjunction Y axis with imaging optics to achievespecified visual (mechanical) steerable range. Geometric Open 120° Thisrefers to the clear cone angle from the center Angle of rotation of themirror such that, when scanning from one extreme to the other, no lightis obstructed. Center of rotation Coincident The system specificationsmay allow the center of w/surface rotation to be below the mirrorsurface. Accuracy vs Set-point ±0.75 arc min Defined over entiresteerable range to ensure all (absolute precision) (0.0125°) desiredsteerable angles can be reached. This specification is a system leveldesign criteria than can change as imaging optical design varies.Repeatability ±0.06 arc min Mirror movements should be highly repeatableto (Absolute) (0.001°) ensure accuracy of system-level calibrations anddistortion corrections. This specification is a system level designcriteria that can change as imaging optical design varies. Beam SteppingTime Small step angle (mech.) 0.52° This specification is a system leveldesign criteria that can change as imaging optical design varies. SmallStep Settling ±0.12 arc min Final system settling should be criteriaaccuracy (0.002°) of final undetectable to user. This specification is atarget system level design criteria than can change as imaging opticaldesign varies. Small step settling time 4.5 ms This specification is asystem level design (max) criteria that can change as display source andframe rate change. Small step settling time 2.93 ms (RMS) Large stepangle (mech.) 10.4° This specification is a system level design criteriathat can change as imaging optical design varies. Large Step Settling±0.25 arc min Final system settling should be criteria accuracy(0.0042°) of final undetectable to user. This specification is a targetsystem level design criteria that can change as imaging optical designvaries. In another embodiment, the large step settling criteria accuracyis ±0.12 arc min (0.002°) of final target. Large step settling time 40ms (for 10.4°) Mirror diameter 8.2 mm Reflectivity >95% Mirror flatnesslambda/4 Operation wavelength Visible (450 nm-640 In some embodiments,may be used also nm) with Short IR (700 nm-950 nm) Typical incident beam4.4 mm diameter Typical angle of 45° incidence with respect to thevertical reference line

TABLE 4 One Embodiment Comment Other Characteristics Footprint 12.5 mm ×12.5 mm Height 4 mm Up to 5 mm Scanning or point & shoot? Point andShoot Mechanical clamping 3x Screw mount slots at edge, with locatingslots Gravitational influence None Magnetic shielding Not-requiredOptical Mirror coating Protected Silver or enhanced aluminum Opticalpower LED illumination, mW May include laser range illumination Controlinterface SPI, I2S, I2C, PWM Power consumption <50 mW (DC) <10 mW (DC)Operating temperature −20° C. to 65° C. At least 0° C. to 40° C. Storagetemperature −40° C. to 85° C. Shock & vibration Shock according torequirements DIN EN 60068-2-27 Cycle life 220M full cycles At least 95Mfull cycles Lifetime 7 years 3 years Compliance with RoHS

Tables 5 and 6 illustrate exemplary optical, physical, and othercharacteristics for a third configuration, associated with the steerablepositioning element of FIGS. 1E and 1F.

TABLE 5 System Design Functional Ranges Considerations Optical andPhysical Characteristics Deflection angle Min: ±2° X axis; ±2° Y Mirrordeflection angle is axis designed in conjunction with Max: imagingoptics to achieve ±15° X axis; ±15° Y axis specified visual steerable(mechanical) range. Geometric Open Angle Min: 60° This refers to theclear cone Max: 160° angle from the center of rotation of the mirrorsuch that, when scanning from one extreme to the other, no light isobstructed. Center of Rotation Offset Min: Coincident The systemspecifications w/surface may allow the center of Max: 2 mm rotation tobe below the mirror surface. Accuracy vs Set-point Min: ±0.05 arc minDefined over entire steerable (absolute precision) Max: ±2.0 arc minrange to ensure all desired steerable angles can be reached. Thisspecification is a system level design criteria than can change asimaging optical design varies. Repeatability (Absolute) Min: ±0.05 arcmin Mirror movements should be Max: ±1.0 arc min highly repeatable toensure accuracy of system-level calibrations and distortion corrections.This specification is a system level design criteria that can change asimaging optical design varies. Beam Stepping Time Small step angle(mech.) 0.52° This specification is a system level design criteria thatcan change as imaging optical design varies. Small Step Settlingcriteria ±0.12 arc min Final system settling should be accuracy (0.002°)of final undetectable to user. This target specification is a systemlevel design criteria than can change as imaging optical design varies.Small step settling time for Min: 1 ms This specification is a system0.52° Max: 10 ms level design criteria that can change as display sourceand frame rate change. Large step angle (mech.) 10.4° This specificationis a system level design criteria that can change as imaging opticaldesign varies. Large Step Settling criteria ±0.25 arc min Final systemsettling should be accuracy (0.0042°) of final undetectable to user.This target specification is a system level design criteria that canchange as imaging optical design varies. In another embodiment, thelarge step settling criteria accuracy is ±0.12 arc min (0.002°) of finaltarget. Large step settling time for Min: 5 ms 10.4° Max: 50 ms Mirrordiameter Min: 4 mm Max: 15 mm Operation wavelength Visible (450 nm-640In some embodiments, may be nm) used also with Short IR (700 nm-950 nm)Typical incident beam Min: 2 mm diameter Max: 8 mm Typical angle ofincidence Min: 20° with respect to the vertical Max: 60° reference line

TABLE 6 Functional Range Comment Other Characteristics Footprint Min: 5mm × 5 mm Max: 17 mm × 17 mm Height Min: 3 mm Max: 8 mm Scanning orpoint & shoot? Point and Shoot Mechanical clamping 2x Screw mount slotsat edge, with locating slots Gravitational influence None Magnetic FieldCompensation 1-2 aux sensors Optical Mirror coating Protected Silver orenhanced aluminum Optical power LED illumination, up to May includelaser 5W range illumination Control interface SPI, I2S, I2C, PWM Powerconsumption <50 mW (DC) <10 mW (DC) Operating temperature −20° C. to 65°C. At least 0° C. to 40° C. Storage temperature −40° C. to 85° C. Shock& vibration Shock according to DIN requirements EN 60068-2-27 Cycle life220M full cycles At least 95M full cycles Lifetime 7 years 3 yearsCompliance with RoHS

Note that the above tables describe embodiments of mechanical, optical,and physical characteristics that describe a set of embodiments usingvarious configurations of a steerable display element using a mirror asthe positioning element. One of skill in the art would understand themodifications which may be made to the above ranges for a differentpositioning element.

FIG. 2 illustrates one embodiment of the exemplary optical system 210,280 and associated processing system 238. In one embodiment, theprocessing system may be implemented in a computer system including aprocessor. In one embodiment, the processing system 238 may be part ofthe display system. In another embodiment, the processing system 238 maybe remote. In one embodiment, the optical system 210, 280 may beimplemented in a wearable system, such as a head mounted display. Thesteerable display image is presented to the user's eye through a righteye steerable display 220 and left eye steerable display 230, whichdirect the steerable display. In one embodiment, the steerable displays220, 230 direct the steerable display image primarily toward the centerof the field of view of the user's eye. In another embodiment, the imagemay be directed to a different location, as will be described below. Thesteerable display image is a high resolution image, in one embodiment.In one embodiment, the steerable display image is a variable resolutionimage. In one embodiment, the variable resolution corresponds to thechange in the maximum resolution perceived by of the user's eye, whichdrops off as it moves further from the center.

The image for the right eye is created using a first display element222. In one embodiment, the display element is a digital micromirrordevice (DMD). In one embodiment, the display element 222 is a scanningmicromirror device. In one embodiment, the display element 222 is ascanning fiber device. In one embodiment, the display element is anorganic light-emitting diode (OLED). In one embodiment, the displayelement 222 is a liquid crystal on silicon (LCOS) panel. In oneembodiment, the display element 222 is a liquid crystal display (LCD)panel. In one embodiment, the display element 222 is a micro-LED ormicro light emitting diode (pLED) panel. In one embodiment, the displayelement is a scanned laser system. In one embodiment, the system is ahybrid system with an off axis holographic optical element (HOE). In oneembodiment, the system includes a waveguide. In one embodiment, thewaveguide is a multilayer waveguide. In one embodiment, the displayelement may include a combination of such elements. FIG. 3 belowdiscusses the display elements in more detail.

In one embodiment, the first display element 222 is located in anear-eye device such as glasses or goggles.

The focus and field of view for the steerable display is set usingintermediate optical elements 224. The intermediate optical elements 224may include but are not limited to, lenses, mirrors, and diffractiveoptical elements. In one embodiment, the focus of the virtual image isset to infinity. In another embodiment, the focus of the virtual imageis set closer than infinity. In one embodiment, the focus of the virtualimage can be changed. In one embodiment, the virtual image can have twoor more focal distances perceived simultaneously.

In one embodiment, the steerable display image is directed primarilytoward the center of the field of view of the user's eye. In oneembodiment, the field of view (FOV) of the steerable display image isgreater than 1 degree. In one embodiment, the FOV of the steerabledisplay image is between 1 degree and 20 degrees. In one embodiment, thesteerable display image may be larger than 5 degrees to addressinaccuracies in eye tracking, to provide the region needed tosuccessfully blend such that the user cannot perceive the blending, andto account for the time it takes to reposition the steerable display forthe various types of eye movements.

In one embodiment, the system further includes a lower resolution fielddisplay image, which has a field of view of 20-220 degrees.

In one embodiment, the steerable display image is projected directlyonto the user's eye using a set of one or more totally or partiallytransparent positioning elements 226. In one embodiment, the positioningelements 226 include a steerable mirror, such as the steerablepositioning element shown in FIG. 1A. In one embodiment, the positioningelements 226 include a curved mirror. In one embodiment, the positioningelements 226 include a Fresnel reflector. In one embodiment, thepositioning elements 226 include a diffractive element. In oneembodiment, the diffractive element is a surface relief grating. In oneembodiment, the diffractive element is a volume hologram. In oneembodiment, the display 220 may include a focal adjustor 223, whichenables the display to show image elements at a plurality of focaldistances in the same frame. In one embodiment, the focal adjustor 223may be an optical path length extender, as described in U.S. patentapplication Ser. No. 15/236,101 filed on Aug. 12, 2016.

A similar set of elements are present for the left eye steerable display230. In one embodiment, the right eye steerable display 220 and the lefteye steerable display 230 are matched. In another embodiment, they mayinclude different elements.

In one embodiment, an eye tracker 240 tracks the gaze vector of theuser, e.g. where the eye is looking. In one embodiment, the eye trackingsystem is a camera-based eye tracking system 240. In one embodiment, thecamera-based eye tracking system 240 includes a holographic opticalelement. In one embodiment, eye tracking system 240 is an infraredscanning laser with a receiving sensor. In one embodiment, the infraredscanning laser eye-tracking system 240 includes a holographic opticalelement. In one embodiment, eye tracking system 240 is an optical flowsensor. Other eye tracking mechanisms may be used. Position calculator245 determines a center of the user's field of view based on data fromthe eye tracking system 240.

In one embodiment, the adjustable positioning elements 226, 236 are usedto adjust the right and left eye steerable display 220, 230 to positionthe image to be directed primarily toward the center of the field ofview of the user's eye. In one embodiment, the adjustable positionelements 226, 236 are used to adjust the right and left eye steerabledisplay 220, 230 to position the eye box or exit pupil toward the centerof the field of view of the user's eye. In one embodiment, the directionof the image is adjusted by changing the angle of a mirror, one of theposition elements 226, 236. In one embodiment, the angle of the mirroris changed by using electromagnetic forces. In one embodiment, the angleof the mirror is changed by using electrostatic forces. In oneembodiment, the angle of the mirror is changed by using piezoelectricforces, as illustrated in FIG. 1A. In one embodiment, the adjustableelement is the image source, or display element 222, 232 which is movedto position the image. In one embodiment, the image is positioned to bedirected to the center of the field of view of the user's eye. Inanother embodiment, another position element 226, 236 may be changed,such as a steering element 226, 236.

A field display 280 communicates with the processing system 238 viacommunication logics 270, 290. In one embodiment, there may be multipledisplays. Here, two field displays are indicated, field display 285 andperipheral display 288. Additional levels of resolution may also beshown. In one embodiment, the field display 280 may include a singlefield display 285 viewed by both eyes of the user, or one field displayper eye. In one embodiment, the field display 280 may have variableresolution. In one embodiment, the resolution drops off toward theoutside of the display 280, corresponding to the drop in the maximumperceived resolution by the eye.

In one embodiment, when the field display 280 is a separate system, syncsignal generator 292 is used to synchronize the display of theindependent steerable display 210 with the display of the field display280. In one embodiment, the sync signal generator 292 is used tosynchronize the adjustable mirror, or other positioning element of thesteerable display with the field display. This results in thesynchronization of the displays. In one embodiment, field display 280includes blender system 294 to blend the edges of the steerable displayimage with the field display image to ensure that the transition issmooth.

In one embodiment, the lower resolution field display image is presentedto the user with a fully or partially transparent optical system. In oneembodiment, this partially transparent system includes a waveguideoptical system. In one embodiment, this partially transparent systemincludes a partial mirror which may be flat or have optical power. Inone embodiment, this partially transparent system includes a diffractiveoptical element. In one embodiment, this image is presented to the userthrough a direct view optical system. In one embodiment, this partiallytransparent system includes inclusions to reflect or scatter light.

In one embodiment of the field display 280, an additional displaysub-system is used to display images in the region of monovisionperipheral display 288. In one embodiment, this sub-system is an LED(light emitting diode) array. In one embodiment, this sub-system is anOLED (organic LED) array. In one embodiment, this display sub-systemuses a scanned laser. In one embodiment, this sub-system uses an LCD(liquid crystal display) panel. In one embodiment the field display 280is an LCOS (liquid crystal on silicon) display. In one embodiment, thefield display is a DLP (digital light processing) display. In oneembodiment, this sub-system has no intermediate optical elements tomanipulate the FOV or focus of the image. In one embodiment, thissub-system has intermediate optical elements. In one embodiment, theseintermediate optical elements include a micro-lens array.

The image data displayed by the steerable display 210 and field display280 are generated by processing system 238. In one embodiment, thesystem includes an eye tracker 240. In one embodiment, an eye tracker240 tracks the gaze vector of the user, e.g. where the eye is looking.In one embodiment, the eye tracking system is a camera-based eyetracking system 240. Alternately, eye tracking system 240 may beinfrared laser based. Foveal position calculator 245 determines a centerof the user's field of view based on data from the eye tracking system240. In one embodiment, the foveal position calculator 245 additionallyuses data from a slippage detection system. Slippage detection in oneembodiment detects movement of the headset/goggles on the user's head,and detects slippage or other shifting which displaces the real locationof the user's eye from the calculated location. In one embodiment, thefoveal position calculator 245 may compensate for such slippage byadjusting the calculated foveal location, used by the system to positionsteerable display.

The processing system 238 in one embodiment further includes fovealposition validator 247 which validates the positioning of the positionelements 226, 236, to ensure that the displays 220, 230 are properlypositioned. In one embodiment, this includes re-evaluating the steerabledisplay location with respect to the center of the field of view of theuser's eye, in light of the movement of the steerable display. In oneembodiment, the foveal position validator 247 provides feedback toverify that the positioning element has reached its target location,using a sensing mechanism. The sensing mechanism may be a camera, in oneembodiment. The sensing mechanism may be gearing in one embodiment. Thesensing mechanism in position validator 247 may be a magnetic sensor.The sensing mechanism may be another type of sensor that can determinethe position of the optical element. In one embodiment, if the actualposition of the steerable display is not the target position, the fovealposition validator 247 may alter the display to provide the correctimage data. This is described in more detail below.

In one embodiment, eye movement classifier 260 can be used to predictwhere the user's gaze vector will move. This data may be used bypredictive positioner 265 to move the steerable display 220, 230 basedon the next position of the user's gaze vector. In one embodiment, smartpositioner 267 may utilize user data such as eye movement classificationand eye tracking to predictively position the displays 220, 230. In oneembodiment, smart positioner 267 may additionally use data aboutupcoming data in the frames to be displayed to identify an optimalpositioning for the displays 220, 230. In one embodiment, smartpositioner 267 may position the display 220, 230 at a position notindicated by the gaze vector. For example, if the displayed frame datahas only a small amount of relevant data (e.g. a butterfly illuminatedon an otherwise dark screen) or the intention of the frame is to causethe viewer to look in a particular position.

The processing system 238 may further include a cut-out logic 250.Cut-out logic 250 defines the location of the steerable display 220, 230and provides the display information with the cut-out to the associatedfield display 280. The field display 280 renders this data to generatethe lower resolution field display image including the cut out of thecorresponding portion of the image in the field display. This ensuresthat there isn't interference between the steerable display image andfield image. In one embodiment, when there is a cut-out, blender logic255 blends the edges of the cutout with the steerable image to ensurethat the transition is smooth. In another embodiment, the steerabledisplay may be used to display a sprite, a brighter element overlaidover the lower resolution field image. In such a case, neither the cutout logic 250 nor blender logic 255 is necessary. In one embodiment, thecut out logic 250 and blender logic 255 may be selectively activated asneeded.

In one embodiment, the system may synchronize the steerable display 210with an independent field display 280. In this case, in one embodiment,synchronization logic 272 synchronizes the displays. In one embodiment,the independent field display 280 is synchronized with the adjustablemirror, or other positioning element of the steerable display 210. Thisresults in the synchronization of the displays. The field display 280may receive positioning data. In one embodiment, there may not be acutout in this case.

In one embodiment, the processing system 238 may include an opticaldistortion system 275 for the steerable display 210 with distortion thatincreases from the center to the edge of the image. This intentionaldistortion would cause the pixels to increase in perceived size movingfrom the center of the image to the edge. This change in perceivedresolution would reduce the amount of processing required, as fewerpixels would be needed to cover the same angular area of the steerabledisplay image. The optical distortion may help with the blending betweenthe steerable display 210 and the field display 280. In anotherembodiment, the steerable display 210 including the optical distortionsystem 275 could be used without a field display. It also provides foran easier optical design, and saves processing on the blending.

In one embodiment, the variable resolution highly distorted image has alarge ratio between center and edge. The total FOV of this display wouldbe large (up to 180 degrees).

In one embodiment, roll-off logic 277 provides a roll-off at the edgesof the display. Roll-off in one embodiment may include resolutionroll-off (decreasing resolution toward the edges of the display area).In one embodiment, this may be implemented with magnification by theoptical distortion system 275. Roll-off includes in one embodimentbrightness and/or contrast roll off (decreasing brightness and/orcontrast toward the edges.) Such roll-off is designed to reduce theabruptness of the edge of the display. In one embodiment, the roll-offmay be designed to roll off into “nothing,” that is gradually decreasedfrom the full brightness/contrast to gray or black or environmentalcolors. In one embodiment, roll-off logic 277 may be used by thesteerable display 210 when there is no associated field display. In oneembodiment, the roll-off logic 297 may be part of the field display 280,when there is a field display in the system.

FIG. 3 illustrates one embodiment of the position elements 300. Theposition elements in one embodiment include a separate position elementfor the right eye and the left eye of the user. In one embodiment,rather than having a steerable element 310 for each eye, the system mayutilize two or more steerable elements 310 for each eye. In oneembodiment, a two element system may include separate steerable elements310 for the X-axis movement and the Y-axis movement for each eye. In oneembodiment, two or more steerable elements 310 may be used, with eachsteerable element 310 having one or more axes of steerability.

The steerable element 310 may comprise one or more of a mirror, prism,Fresnel lens, or other element which is positioned so that light can bedirected to a particular location. In one embodiment, the steerableelement 310 is a curved mirror.

The X-axis attachment 320 provides the physical moving element forrotating around the X-axis, while the Y-axis attachment 350 provides themoving element for pivoting around the Y-axis. In one embodiment, themoving elements are pivots 150 and gimbals 155.

The X-axis controller 330 and Y-axis controller 360 control themovement, while the X-axis actuator 340 and Y-axis actuator 370 providethe physical movement. Piezoelectric elements in one embodiment are thecontrollers. The data for the movement comes from microprocessor 390. Inone embodiment, microprocessor 390 is part of the main control circuitryof the steerable display.

In one embodiment, the system also includes a position validator 380which verifies the actual position of the steerable element 310 alongthe X and Y axes. In one embodiment, validator 380 comprises a magneticsensor, which senses the movement of magnets associated with the movableelement. In another embodiment, the validator 380 may be coupled to theactuators 340, 370 or attachment 320, 350, and determine the position ofthe steerable element 310 based on the physical position of the elementssupporting the steerable element 310. Other methods of determining theactual position of the steerable element 310 may be used.

In one embodiment, the validator 380 provides data to the microprocessor390. The microprocessor may compare the data from the controllers 330,360 with the data from the position validator 380. This may be used forrecalibration, as well as to identify issues with the positioning ofsteerable element 310. In one embodiment, to enable position validator380, the bottom of the steerable element 310 has markings which are usedby position validator 380 to determine the actual position of thesteerable element 310.

FIG. 4C illustrates one embodiment of the movement of the display overtime. In one embodiment, the movement may correspond to the location ofthe user's fovea as the user's eye moves. In any time instance, there isa small zone, to which the image is displayed. The location of the 5degree display of high resolution (in one embodiment) is focused on thecenter of the user's field of view. In one embodiment, a low resolutionfield image provides a large field of view. But because the relativeresolution of the eye outside the foveal area is lower, the userperceives this combination image, including the small high resolutionsteerable image and the larger low resolution field image as highresolution across the large field of view.

FIG. 4A is a flowchart of one embodiment of utilizing the steerabledisplay. The process starts at block 410. In one embodiment, prior tothe start of this process the display system is fitted to the user. Thisinitial set-up includes determining the interpupillary distance (IPD)and any prescription needed, to ensure that the “baseline” display forthe user is accurate.

At block 415, the user's eyes are tracked. In one embodiment, an IRcamera is used for tracking eyes. In one embodiment, eye trackingidentifies the gaze vector of the user, e.g. where the user is focused.

At block 420, the system calculates the gaze vector of the user. The eyetracking may identify left and right eye gaze vector/angle, and gazecenter (derived from the L/R eye gaze vectors). In one embodiment, theeye tracking may determine the location (X, Y, Z) and orientation (roll,pitch, yaw) of the left and right eyes relative to a baseline referenceframe. The baseline reference frame is, in one embodiment, establishedwhen the display is initially fitted to the user and the user'sinterpupillary distance, diopters, and other relevant data areestablished.

At block 420, the location of the fovea is determined based on the gazevector data. In one embodiment, the fovea location includes coordinates(X, Y, Z) and orientation (roll, pitch, yaw) for each eye.

At block 425, the process determines whether the steerable displayshould be repositioned. This is based on comparing the current positionof the steerable display with the user's gaze vector or the intendedposition of the image. If they are misaligned, the system determinesthat the steerable display should be repositioned. If so, at block 430,the display is repositioned. The repositioning of the display isdesigned so the movement of the steerable display is not perceived bythe user. In one embodiment, this may be accomplished by using a mirrorthat is fast enough to complete the movement in a way that the usercannot perceive it. In one embodiment, this may be accomplished bytiming the movement to the user's blink or eye movement. In oneembodiment, if the intended display is moved more than a particulardistance, the display is blanked during the move. This ensures that theuser does not perceive the movement. In one embodiment, the particulardistance is more than 0.5 degrees. In one embodiment, the intendeddisplay is not blanked if the movement is occurring while the user isblinking. Note that although the term “repositioning” is used, thiscorresponds to the movement of the positioning elements, to adjust theposition of the display.

The process then continues to block 435, whether or not the display wasrepositioned.

At block 435, optionally the system cuts out the portion of the fielddisplay image that would be positioned in the same location as thesteerable display image. This prevents the field display frominterfering with the steerable display. The cut-out, in one embodiment,is performed at the rendering engine. In another embodiment, the imagemay be a sprite or other bright image element which does not need acut-out to be clear. In that instance, this block may be skipped. In oneembodiment, the cut-out is skipped if the user eye tracking indicatesthat the user's gaze has moved substantially from the baselinereference. The baseline reference is the user's default gaze position,from which the movement of the gaze is tracked. A substantial movementfrom the baseline reference means that the system cannot determine theuser's correct gaze position. In this instance, in one embodiment, thesteerable display image may be dropped, or the steerable display may beturned off momentarily. In one embodiment, this may be done by blankingthe steerable display so that it is not seen by the user. In variousembodiments, this may be done by disabling a backlight, disabling laseror LED illumination source, blanking the pixels, or through anothermethod.

At block 440, in one embodiment, the edges between the steerable displayimage and the field image are blended. This ensures a smooth andimperceptible transition between the field image and the steerabledisplay image. At block 445, the hybrid image is displayed to the user,incorporating the steerable display and the field display. The processthen returns to block 410 to continue tracking and displaying. Note thatwhile the description talks about a steerable display image and a fieldimage, the images contemplated include the sequential images of video.Note also that while this description utilizes a combination of thesteerable display and a field display in some embodiments, the steerabledisplay may be used without the presence of a field display. In thoseinstances, the process may include only blocks 415 through 430.

FIG. 4B illustrates one embodiment of the corrective actions which maybe taken when the display position validation indicates that the actuallocation of the steerable display does not match the intended location.The process starts at block 450.

At block 452, the steerable display positioning is initiated. In oneembodiment, this corresponds to block 430 of FIG. 4A. Returning to FIG.4B, at block 454, the actual position of the steerable display isverified. In one embodiment, one or more sensors are used to determinethe location and orientation of the steerable display. In oneembodiment, the sensors may include cameras, mechanical elementsdetecting the position of the adjustable mirror or other positioningelement, etc. This is done, in one embodiment, by the position validator380 of FIG. 3.

At block 456 the process determines whether the steerable display iscorrectly positioned. Correct positioning has the steerable display inthe calculated location, to display the image in the appropriatelocation for the user. If the steerable display is correctly positioned,at block 464 the image is displayed. In one embodiment, this includesdisplaying a hybrid image including the steerable display image in thecalculated location and the associated field display image, as discussedabove with respect to FIG. 4A. The process then ends at block 475.

If, at block 456, the process determines that the steerable display wasnot correctly positioned, the process continues to block 458.

At block 458, the process determines whether there is enough time forthe steerable display to be repositioned. This determination is based ona distance that needs to be moved, the speed of movement, and time untilthe next image will be sent by the processing system.

In one embodiment, it also depends on the eye movement of the user. Inone embodiment, the system preferentially moves the steerable displaywhile the user is blinking, when no image is perceived. In oneembodiment, the repositioning occurs within a blanking period of thedisplay. For example, a movement of just one degree along one coordinatetakes less time than moving the steerable display significantly and inthree dimensions. If there is enough time, the process returns to block452 to reposition the steerable display. Otherwise, the processcontinues to block 460.

At block 460, the process determines whether the actual position of thesteerable display is within range of the intended position. In oneembodiment, “within range” in this context means that the system iscapable of adjusting the display for the difference. If it is withinrange, the process continues to block 462.

At block 462, the data processed for display on the steerable image isadjusted for rendering in the actual position. The adjusted image isthen displayed at block 464. For example, in one embodiment, theoriginal calculated image may be rendered in the wrong location if theposition difference is very small, without causing visual artifacts. Inanother embodiment, the image may be adjusted to render appropriately atthe actual location. For example, the image may be cropped, brightened,distorted, contrast adjusted, chromatic coordinate (white point)adjusted, cropped, and laterally shifted to account for the locationdifference.

In one embodiment, for a hybrid display, the radial location of the edgeblending may be shifted or changed. In one embodiment, the system mayover-render, e.g. render 5.5 degrees of visual image for a 5-degreesteerable display, enabling a shift of 0.5 degrees without needingre-rendering.

If the steerable display is not within range, at block 466, in oneembodiment the frame data is sent to the field display for rendering. Atblock 468, in one embodiment the steerable display image is notdisplayed. In one embodiment, the frame is dropped. In anotherembodiment, the steerable display is blanked momentarily. In oneembodiment, the steerable display is not considered within range if theuser eye tracking indicates that the user's gaze has moved too faroutside of the baseline reference.

At block 470, one embodiment, the field display image is rendered,without the image cut-out and without the display or rendering of thesteerable display image. At block 472, the field display image isdisplayed. The process then ends.

FIG. 5 is a flowchart of one embodiment of utilizing the steerabledisplay, where positioning is not dependent on the user's gaze vector.This may be applicable, for example, when the display is a heads-up typeof display, or a sprite, or the only bright element on an otherwise darkdisplay. Other reasons to provide positioning not based on the user'sgaze vector may be found. In one embodiment, this configuration may becombined with the configuration of FIG. 4A discussed above, in which thepositioning is based on the gaze vector. That is, the same system mayvary between being gaze-vector based and not.

The process starts at block 510. In one embodiment, prior to the startof this process the display system is fitted to the user.

At block 515, the position for the steerable display is determined. Thisdetermination may be made based on external data (for example in avirtual reality display), or other determinations. In one embodiment,this decision may be made based on processor data.

At block 520, the process determines the current position of thesteerable display.

At block 525, the process determines whether the steerable displayshould be repositioned. This is based on comparing the current positionof the steerable display with the intended position of the image. Ifthey are misaligned, the system determines that the steerable displayshould be repositioned. If so, at block 530, a display repositioning istriggered. The repositioning of the display is designed so the movementof the steerable display is not perceived by the user, in oneembodiment. In one embodiment, this may be accomplished by using amirror that is fast enough to complete the movement in a way that theuser cannot perceive it, as described above. In one embodiment, this maybe accomplished by timing the movement to the user's blink or eyemovement. In one embodiment, if the intended display is moved more thana particular distance, the display is blanked during the move. Thisensures that the user does not perceive the movement. In one embodiment,the particular distance is more than 0.5 degrees. In one embodiment, theintended display is not blanked if the movement is occurring while theuser is blinking. Note that although the term “repositioning” is used,this corresponds to the movement of the positioning elements, to adjustthe position of the display.

The process then continues to block 535, whether or not the display wasrepositioned.

At block 535, optionally the system cuts out the portion of the fielddisplay image that would be positioned in the same location as thesteerable display image. This prevents the field display frominterfering with the steerable display.

The cut-out, in one embodiment, is performed at the rendering engine. Inanother embodiment, the image may be a sprite or other bright imageelement which does not need a cut-out to be clear. In that instance,this block may be skipped.

At block 540, in one embodiment, the system determines whether the edgesbetween the steerable display image and a field image should be blended.This ensures a smooth and imperceptible transition between the fieldimage and the steerable display image. This may not be relevant whenthere is no field display, or when the steerable display is a sprite orother overlay element. If the system determines that the edges should beblended, at block 545, the edges are blended.

At block 550, the image from the steerable display is displayed to theuser, optionally incorporating data from the field display. The processthen returns to block 510 to continue tracking and displaying. Note thatwhile the description talks about a steerable display image and a fieldimage, the images contemplated include the sequential images of video.Note also that while this description utilizes a combination of thesteerable display and a field display in some embodiments, the steerabledisplay may be used without the presence of a field display.

FIG. 6 is a flowchart of one embodiment of controlling the use of thesteerable element. In one embodiment, the system determines the type ofeye movement, saccade or smooth pursuit. For smooth pursuit, in oneembodiment, the system moves one frame at a time, and matches the eyemovement so that the steerable display may be on during the movement. Inone embodiment, this can be done for up to a three degree per framemovement. For eye movement faster than that, in one embodiment, thesteerable display may be blanked. For a saccade movement, in oneembodiment the system blanks the steerable display temporarily formovement, to avoid visual aberrations. The system is designed to have asettling time that is faster than the user's eye. Thus, the display isdesigned to be active again by the time the eye has settled after asaccade movement, and is back to full resolution. FIG. 6 illustrates oneembodiment of moving the steerable display for a saccade or other fastmovement.

The process starts at block 605. In one embodiment, this process runswhenever the steerable display is active. At block 610, the user's gazeposition is monitored for the steerable display. In one embodiment, thesteerable display is directed to the user's fovea.

At block 615 a new gaze position is determined. In one embodiment, thegaze position is identified using a camera directed at the user's eye.

At block 620, the degree of movement needed for the steerable display tomatch the new gaze vector is identified.

At block 625, the time to move the steerable display to the new locationis determined. In one embodiment, a look-up table is used. In oneembodiment, the “gaze vector” determined may be a plurality of gazevectors over time, as in a smooth pursuit eye movement.

At block 630, the steerable display is blanked, and the movement isstarted. In one embodiment, the movement is only started after thesteerable display is blanked. The steerable display may be blanked inone embodiment by turning off a light source. In another embodiment thesteerable display may be turned off by blanking the mirror. In anotherembodiment, the steerable display may be blanked by disabling abacklight or illumination. In another embodiment, the steerable displaymay be blanked by setting the pixels to black.

At block 635, the steerable display is moved. During this time, sincethe steerable display is blanked, in one embodiment, the field displayis filled in to cover the full display area. In another embodiment,there may not be a field display in which case this does not apply.

At block 640, the process determines whether the time has elapsed tocomplete the calculated movement, in one embodiment. If not, the processcontinues to move at block 635.

If the time has elapsed, in one embodiment, the system provides a signalto activate the steerable display, at block 645. In another embodiment,the signal timing may be based on the movement data from themicroprocessor and position verifier.

When the signal to activate n the display is received, at block 645, atblock 650 the process verifies that the display has stopped moving andhas settled. Settling means that the display is steady and is notvibrating as a result of the movement. In one embodiment, this is aclosed loop determination made by the microprocessor in the display.

If the display has settled, at block 655 the steerable display isactivated. In one embodiment, if there is a field display it may be cutout for the area in which the steerable display image is shown. Theprocess then continues to block 610, to continue monitoring the gazeposition of the user, and to determine a new gaze position. In this way,the steerable display is moved to match the user's gaze, while providingno visual indicators of movement.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will, however,be evident that various modifications and changes may be made theretowithout departing from the broader spirit and scope of the invention asset forth in the appended claims. The specification and drawings are,accordingly, to be regarded in an illustrative rather than a restrictivesense.

1. A steerable display system comprising: a display element; a positionelement to position an image generated by the display element theposition element comprising: steerable element; an X-axis controller topivot the steerable element around an X-axis; a Y-axis controller topivot the steerable element around a Y-axis; wherein a movement of thesteerable element is such that a user does not perceive motion; suchthat the steerable element has a range of motion that enables thesteerable display to be positioned and repositioned at a plurality oflocations within a field of view of the user.
 2. The steerable displaysystem of claim 1, further comprising: a position validator, to verifyan actual position of the steerable element and to adjust steerabledisplay image data when the actual position is not an intended position.3. The steerable display system of claim 1, wherein the steerableelement comprises one or more of: adjustable mirror, tunable prism,acousto-optical modulator, adjustable display panel, a curved mirror, adiffractive element, and a Fresnel reflector.
 4. The steerable displaysystem of claim 1 wherein: the steerable display has a monocular fieldof view of at least 1 degree, positioned within a scannable field ofview of at least 20 degrees.
 5. The steerable display system of claim 1,further comprising: an actuator to move the steerable element, theactuator comprising one of a piezo-electric element, a magnetic element,a nanomotor.
 6. The steerable display system of claim 5, wherein theactuator has an absolute precision of +/−0.75 arc minute, and a relativeprecision of 0.06 arc minute.
 7. The steerable display system of claim5, wherein a settling time is less than 2 ms.
 8. The steerable displaysystem of claim 1, wherein the steerable element is a mirror having adiameter between 5 mm and 15 mm.
 9. The steerable display system ofclaim 1, wherein the position element is smaller than 5 mm×12 mm×12 mm.10. A steerable display system comprising: a moveable display element;position element to move the display element, to position an imagegenerated by the display element, the position elements comprising:flexible arms supporting the moveable display element; a controller topivot the steerable element around the axis-using the flexible arm;wherein a movement of the steerable element is such that a user does notperceive motion; such that the steerable element has a range of motionthat enables the steerable display to be positioned and repositioned ata plurality of locations within a field of view of the user.
 11. Thesteerable display system of claim 10, further comprising: a positionvalidator, to verify an actual position of the steerable element and toadjust steerable display image data when the actual position is not anintended position.
 12. The steerable display system of claim 10, whereinthe steerable element comprises one or more of: adjustable mirror,tunable prism, acousto-optical modulator, adjustable display panel, acurved mirror, a diffractive element, and a Fresnel reflector.
 13. Thesteerable display system of claim 10 wherein: the steerable display hasa monocular field of view of at least 1 degree, positioned within ascannable field of view of at least 20 degrees.
 14. The steerabledisplay system of claim 10, further comprising: an actuator to move thesteerable element, the actuator comprising one of a piezo-electricelement, a magnetic element, a nanomotor.
 15. The steerable displaysystem of claim 14, wherein the actuator has an absolute precision of+/−0.75 arc minute, and a relative precision of 0.06 arc minute.
 16. Thesteerable display system of claim 14, wherein a settling time is lessthan 2 ms.
 17. The steerable display system of claim 10, wherein thesteerable element is a mirror having a diameter between 5 mm and 15 mm.18. The steerable display system of claim 10, wherein the positionelement is smaller than 5 mm×12 mm×12 mm.
 19. A steerable display systemcomprising: a display element; two pivots around which the displayelement can move in all directions; piezo-electric elements to drive thepivots, to move the display element; magnets and associated magneticsensors to determine a position of the display element; wherein aposition of the magnets counterbalances the piezo electric elements,such that the display element is balanced in weight.